The invention is based on a braking device for an electric motor.
From German Patent Disclosure DE 198 60 396 A1, a braking device for a direct current series wound motor is known that makes it possible to brake the rotor of the direct current series wound motor upon shutoff. To that end, the known braking device has a rockerlike brake element with a brake arm and a disengagement arm; the rockerlike brake element is pivotable between a braking position and an operating position. A brake shoe is secured to the brake arm, and the brake arm with the brake shoe is prestressed in the direction of the rotor by a compression spring and brakes the rotor in the braking position.
The disengagement arm of the rockerlike brake element, conversely, has the task of lifting the brake arm and the brake shoe from the rotor in operation so that the rotor can rotate freely. To that end, the disengagement arm and a yoke part of the stator form an air gap, so that when current is supplied to the stator winding, the disengagement arm is pulled against the yoke part, lifting the brake shoe from the rotor.
In the known braking device, the brake arm with the brake shoe is disposed on the rockerlike brake element on the leading end relative to the direction of rotation of the rotor, while the disengagement arm is conversely disposed on the brake element on the trailing end. This arrangement of the brake shoe on the leading end offers the advantage that the braking force acting on the brake shoe exerts a torque on the brake element, as a result of which the contact pressure generated by the spring is reinforced.